Embodiments of the inventive concepts described herein relate to an underground localization method and a system therefor, and more particularly, to an underground localization method of correcting a location using re-measurement of physical information and a system therefor.
Unconventional resources are collectively called “oil or natural gas resources” in which it is impossible to be developed and produced using conventional technology because they have unique geological structures and unique lying shapes. Because the unconventional resources are distributed as a continuous form throughout wide areas, they need advanced development technology. The unconventional resources are classified into unconventional oil resources and unconventional natural gas resources according to their properties. The unconventional oil resources are classified into oil sand, extra heavy oil, oil shale, shale oil and the like according to lying shapes. The unconventional natural gas resources are classified into shale gas, tight gas, coal bed methane gas, gas hydrate and the like according to lying shapes.
These unconventional resources need specialized technology suitable for characteristics according to respective resources. The reason why the unconventional resources are recently highlighted is that a variety of technologies, which may be approached to unique geological structures of the unconventional resources and may mine and collect big oil and natural gas therefrom, may be developed and applied in their production process.
Directional drilling technology is highlighted to mine the unconventional resources among the variety of technologies. The directional drilling technology is drilling technology for changing an excavation direction and performing excavation to a target point when drilling a reservoir which exists in a lower portion of each of areas, such as a mountainous area or a lower area of a lake where it is difficult to work by vertical drilling and a densely populated area and a water conservation zone where it is legally impossible to drill.
To perform this drilling work, a drilling base is made by drilling a shallow hole in the ocean floor, inserting a casing into the hole, and hardening the casing with cement. Thereafter, a blow out preventer (BOP) is connected to a riser and the BOP is lowered through a moonpool molded in the center of a drill ship. After the drilling base, the BOP, and the riser are combined with one another, a drill pipe is inserted into an empty space in the riser to perform a real drilling work. As drill bits are on the end of the drill pipe, they may efficiently destroy rocks using a torque of a top drive.
Korean Patent No. 10-0409048 relates to a drilling apparatus for discontinuity orientation measurements and describes technology about a drilling apparatus which may rotate an outer pipe of the drilling apparatus of a double pipe type which is divided into an inner pipe and the outer pipe and may perform excavation in a direct direction.
As such, the directional drilling apparatus is an apparatus which may perform excavation in a desired direction, and must ascertain its current position in an underground space and may determine whether the desired direction is any direction. Therefore, the directional drilling apparatus must be accompanied by the development of an underground localization technology.
However, because the underground environment is blocked in all directions by soil, it is impossible to perform wireless communication of a global positioning system (GPS) and the like. Sensors, such as a vision sensor (e.g., a camera, etc.) or laser distance measurement sensor, which are used in localization in a general robot field, may not used under the underground environment.
For this reason, conventional underground localization technologies may use angular velocities or accelerations which may be measured for itself using an inertial measurement unit (IMU). However, because there is no method of compensating error accumulation of sensors in a drill environment with strong vibration, it is difficult to accurately perform underground localization.